DESCRIPTION: The goal of the present proposal is to develop, extend, and enhance methods of likelihood analysis of pedigree data, including both segregation and linkage analysis. This will be done using PAP, the Pedigree Analysis Package, a series of Fortran programs that have been developed and modified over the past 15 years. There are four specific aims, each with two specific projects. The first aim involves developing new algorithms to model mitochondrial inheritance and to model the effect of selection. The second aim is to develop new methods of screening for multilocus effects on phenotypes and to develop simulation-based goodness-of-fit tests. The third aim is to extend current programs to implement a newer ascertainment correction scheme, and to incorporate replicate and MZ twin data. The final aim is to distribute, support, and update PAP for the scientific community, and to develop revision 5 of the entire PAP package.